Variation in powder from bottle to bottle

[JasonF]

Newbie reloading question...

Last weekend, I found a load that my 7mm-08 seemed to like (0.5" group) and which had a 140 grain Nosler BT travelling at a respectable velocity (2860fps), using 2206H. Went home and loaded up some more using identical components, except for a new bottle of powder. Shot the loads today, using the same rest set up in ideal conditions. These loads were down a bit on velocity (about 70fps), and accuracy wasn't acceptable (1.5" group), but interestingly the ES was about half (14fps).

I can only assume the powder is to blame. Is it normal to have such a wide variation between bottles of powder? Do I need to fully rework my loads for every new bottle (if so, I am going to buy in bulk).

[Seddo]

ADI powder can have a large variation between powder lots. there are lots of stories about people going to a nationals and not making major power factor with their handguns just because they bought a new tin of AP100. I cant imagine rifle powders would be any different.

if you get a good load make sure you buy a 4kg tub of find another tub with the same batch number on it. THe other thing to do is buy a few smaller tubs and then mix them together. I knew a person who bought AP100 in 2kg tins, when he was half way through the tin he bought another one and mixed them together. His reasoning was he was halving the variation between pwder lots.

[daisy]

Just a thought. I use 2209 in my 7-08 that I shoot silhouette with and most blokes us it or 2208 of the ADI powders. The higher load density might help you.

Daisy

[macca]

It can be a problem.I prefer 2208 to 2206h and 2209 above both as it seems to get less variation.
As seddo said get a large quantity of the same batch.

[Curtley78]

G'day Jason,

In regard to what Daisy has posted, I also use 2209 in my 7mm08 imp and recently found a cracking load using 150 grn Sierra Match Kings. If you can afford it then you should buy in bulk lot. Be certain to trial the 2209.

Regards

Sean

[a.JR]

Jason , It is an industry standard to produce lot to lot gunpowders with a 10 percent variation in both AOL pressure and projectile speeds at a preset level .. The different makes blend to achieve less than the 10 percent level ,but there are certain batchs that will always be different .. I had 1 new lot of 2209 that proceded to destroy the cases when the only thing i changed was the powder batch ..Info i recieved from good sources was the new batch would be 2 to 300 fps slower and nearly 1000psi higher in pressure that the previous batch i had been using .. I now always test a given batch that is currently available to make sure it's what i want and then buy enough to wear out that particular barrel . There are batchs with special quality's for competition purposes and these should be purchased in as big a lot as you can afford or store. Hope this helps..JR..Jeff Rogers

Newbie reloading question...

Last weekend, I found a load that my 7mm-08 seemed to like (0.5" group) and which had a 140 grain Nosler BT travelling at a respectable velocity (2860fps), using 2206H. Went home and loaded up some more using identical components, except for a new bottle of powder. Shot the loads today, using the same rest set up in ideal conditions. These loads were down a bit on velocity (about 70fps), and accuracy wasn't acceptable (1.5" group), but interestingly the ES was about half (14fps).

I can only assume the powder is to blame. Is it normal to have such a wide variation between bottles of powder? Do I need to fully rework my loads for every new bottle (if so, I am going to buy in bulk).

[Knackers]

Thanks for the question JasonF, cause the replies have taut me something, I had also wondered about batch to batch consistency.

[JasonF]

Thanks for the replies guys. I am looking into a 4kg tub.

For those who recommended 2209 in my 7mm08 - I tried 2209 and 2208 first, but got much better velocity from 2206H (or the first bottle anyway) in my 1 in 10" twist barrel with 140 gr and 120 gr Nosler BTs.

[robin]

Befor you blame variations in velocity on powder batch variations it might pay to check your chronograph. Cheap chronographs are notorious for giving velocity variations with changes in light / tempreture.
RobH

[macca]

Whilst chronys can and do vary I think my primers falling out of the cases was a sure sign that a new batch of 2208 was running a bit hotter then the last one I used. They were also printing 1 to 2 MOA higher on the target.

[Rath]

Jason, how long is your barrel? I could not get the 130gr Barnes I was using out of my .308 and it's 19' barrel higher than 2850fps (max load 2208). With a max load of 2206H I got 3080fps. However from my 24' barrel using 2208 I get 2930fps ave. I think the faster burn time of 06H is a big benefit in short barrels.

[mistit]

Whilst chronys can and do vary I think my primers falling out of the cases was a sure sign that a new batch of 2208 was running a bit hotter then the last one I used. They were also printing 1 to 2 MOA higher on the target.

the beauty of loading like this macca is you dont have to use a decapping pin in your neck die long shot showed me this trick on the last trip away,the downside was the mallet he used to open the action the whole trip

[JasonF]

Befor you blame variations in velocity on powder batch variations it might pay to check your chronograph. Cheap chronographs are notorious for giving velocity variations with changes in light / tempreture.
RobH

That is a good point - I checked the loads again yesterday with the chrono in the shade and got slightly higher velocities for the same load. Adding a bit more powder had me back at the accuracy node which was good. I also think a fresh battery in the chrono is needed.

Jason, how long is your barrel? I could not get the 130gr Barnes I was using out of my .308 and it's 19' barrel higher than 2850fps (max load 2208). With a max load of 2206H I got 3080fps. However from my 24' barrel using 2208 I get 2930fps ave. I think the faster burn time of 06H is a big benefit in short barrels.

It is a 24" Lilja 1 in 10" twist. The 2209 max load gave me 2750fps but lots of unburnt powder out the muzzle. 2208 was a bit better 2790fps. A slightly below max load of 06H gives 2860 depending on the bottle. I am operating on the assumption that the slightly slower twist favours faster powders.

[morerams]

A few years ago when I was doing a lot of chronographing of loads, and usually borrowing a chrono, I always checked the chrono first by shooting my 22 with the same batch of ammo. If it didn't give me the normal velocity I would start checking the battery, sunshades etc to sort it out before shooting the more important stuff.